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J Clin Periodontol. 2007 Sep;34(9):756-61.

Reported methodological quality of split-mouth studies.

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Biostatistical Centre, Catholic University Leuven, Leuven, Belgium.



Hujoel & Moulton previously questioned the reported quality of split-mouth studies. Since then, there has been little enquiry into the methodology of this study design. The aim was to conduct a systematic review of the reported methodology of clinical studies using a split-mouth design published in dental journals over a 1-year period (2004).


An extension of the CONSORT guidelines for cluster-randomized designs was used to evaluate quality. We evaluated the methods used and quality of reporting split-mouth studies.


Thirty-four studies were eligible for this review. The results showed that many papers lack essential qualities of good reporting, e.g. five of 34 papers gave the rationale for choosing a split-mouth design, 19 of 34 (56%) used appropriate analytical statistical methods and only one of 34 presented an appropriate sample size calculation. Of the five studies that used survival analysis, none of them used a paired approach.


Despite some progress in statistical analysis, if the reporting of studies represents the actual methodology of the trial, this review has identified important aspects of split-mouth study design and analysis that would benefit from development.

[Indexed for MEDLINE]

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